Ace point game bear-in - O's turn

[Walt]

XGID=-cABBBCBC------a--abbbbb--:1:1:-1:21:4:1:0:5:10

X:Player 1 O:Player 2
Score is X:4 O:1 5 pt.(s) match.
+12-11-10--9--8--7-------6--5--4--3--2--1-+
| O O | | O O O O O |
| | | O O O O O |
| | | |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | X O | +---+
| X X | | X X X X O | | 2 |
| X X | | X X X X X O | +---+
+13-14-15-16-17-18------19-20-21-22-23-24-+
Pip count X: 82 O: 129 X-O: 4-1/5
Cube: 2, X own cube
O to play 21

The question came up whether it would be correct for O to hit after X
slots the two point. So, what do you do here as O?


--
//Walt

[Bradley K. Sherman]

Walt <walt_...@yahoo.com> wrote:
>Score is X:4 O:1 5 pt.(s) match.
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> | O O | | O O O O O |
> | | | O O O O O |
> | | | |
> | | | |
> | | | |
> | |BAR| |
> | | | |
> | | | |
> | X | | X O | +---+
> | X X | | X X X X O | | 2 |
> | X X | | X X X X X O | +---+
> +13-14-15-16-17-18------19-20-21-22-23-24-+

> X:82 O:129, O to play 21

10/8,7/6

--bks

[badgolferman]

I think O should hit. Even if O ends up crunching his board he should
be able to take the 23-point and cause trouble later. If O doesn't hit
X can probably hold out for 3-4 more rolls before O can escape. By
then O's home board will be crunched anyway.

24/23*, 10/8.

[crf]

> I think O should hit.

I do, too, but for a different reason -- to try and force X to hit, and as many times as possible! Instead of crunching while X takes their time coming home, O wants to wait on the bar for a shot or at least get a little more timing. With X 1 away, O doesn't care how many backgammons it costs to eek out any sort of win to stay alive.

24/23*, 3/1.

[Tim Chow]

On May 21, 4:12 am, crf <friesen.cr...@gmail.com> wrote:
> 24/23*, 3/1.

That's a very imaginative play but I suspect that reducing from a five-
prime to a three-prime is too costly. Even if X hits, O will be a
favorite to enter from the bar. I'd be delighted to be proved wrong
though---that would make this a very interesting position.

I'd go with badgolferman's play of 24/23* 10/8.

---
Tim Chow

[Walt]

crf has the right idea here. Gammons don't matter, so try to force X to
hit so that his board crunches while O sits on the bar. The other
hitting plays are respectable choices. Not hitting is a blunder.

BTW, I didn't know the answer when I posted the problem so no QF at work
here, even if the best play is somewhat counter intuitive.

XGID=-cABBBCBC------a--abbbbb--:1:1:-1:21:4:1:0:5:10

X:Player 1 O:Player 2
Score is X:4 O:1 5 pt.(s) match.
+12-11-10--9--8--7-------6--5--4--3--2--1-+
| O O | | O O O O O |
| | | O O O O O |
| | | |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | X O | +---+
| X X | | X X X X O | | 2 |
| X X | | X X X X X O | +---+
+13-14-15-16-17-18------19-20-21-22-23-24-+
Pip count X: 82 O: 129 X-O: 4-1/5
Cube: 2, X own cube
O to play 21

1. Rollout� 24/23* 3/1 eq:-0.699
Player: 14.44% (G:0.56% B:0.02%)
Opponent: 85.56% (G:50.80% B:21.53%)
Confidence: �0.006 (-0.706..-0.693) - [100.0%]
Duration: 9 minutes 24 seconds

2. Rollout� 24/23* 7/5 eq:-0.748 (-0.49)
Player: 11.88% (G:0.69% B:0.03%)
Opponent: 88.12% (G:41.21% B:11.62%)
Confidence: �0.005 (-0.752..-0.743) - [100.0%]
Duration: 7 minutes 04 seconds

3. Rollout� 24/23* 10/8 eq:-0.751 (-0.051)
Player: 11.83% (G:0.60% B:0.03%)
Opponent: 88.17% (G:43.67% B:14.15%)
Confidence: �0.005 (-0.756..-0.746) - [0.0%]
Duration: 7 minutes 26 seconds



4. Rollout� 24/23* 6/4 eq:-0.763 (-0.064)
Player: 11.47% (G:0.34% B:0.01%)
Opponent: 88.53% (G:47.08% B:17.01%)
Confidence: �0.005 (-0.768..-0.759) - [0.0%]
Duration: 6 minutes 32 seconds

5. Rollout� 7/5 2/1 eq:-0.783 (-0.084)
Player: 10.62% (G:0.19% B:0.00%)
Opponent: 89.38% (G:35.49% B:7.56%)
Confidence: �0.004 (-0.787..-0.780) - [0.0%]
Duration: 4 minutes 24 seconds

6. Rollout� 10/7 eq:-0.791 (-0.092)
Player: 10.15% (G:0.27% B:0.00%)
Opponent: 89.85% (G:35.49% B:7.59%)
Confidence: �0.004 (-0.795..-0.788) - [0.0%]
Duration: 2 minutes 50 seconds


� 1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


eXtreme Gammon Version: 2.10, MET: Kazaross XG2


--
//Walt

[Freeven]

O's chances are slim no matter what he plays, but hitting looks right to
me as it opens up some possibilities. For one thing, sending X back puts
O back in the priming battle. For another, O may be able to advance his
anchor to the 23pt, or to leap a checker when X clears his 8pt. None of
these things are likely, but equity is where you find it, and every
little bit helps.

The bigger question, for me, is how to play the 2. I've been focusing
almost exclusively on playing dmp matches for the past couple of months,
and this is a theme that comes up surprisingly often when gammons don't
matter and games must be played all the way to the end. I'm pretty
confident that 3/1 is best. This forces X to hit when he enters, which
increases O's chances of dancing or making the 23pt. Either of these
things add to O's timing prospects -- not much, but again, you work with
what you've got. The more checkers O gets sent back, the better,
especially if it takes him a while to enter. These sorts of plays not
only tend to be right, but clearly right.